This invention relates generally to gas turbine engines and more particularly, to a pulse detonation system for a gas turbine engine.
At least some known pulse detonation systems use a series of repetitive detonations within a detonation chamber to produce a high pressure exhaust. More specifically, a fuel and air mixture is periodically detonated within a plurality of tubes within the detonation chamber to create hot combustion gases which cause pressure waves to propagate at supersonic speeds within the tubes and chamber. The pressure waves compress the hot combustion gases, which increases a pressure, density, and a temperature of the gases to produce thrust as the pressure waves pass the exit of an open end of the detonation chamber.
Gas turbine engines producing thrust using pulse detonation systems typically have a higher thrust to weight ratio because they are generally smaller and weigh less than conventional gas turbine engines. In addition, pulse detonation engines may include fewer rotating parts, produce lower emissions, and be more fuel efficient than conventional gas turbine engines. Pulse detonation engines also may not suffer stall and startup problems that may be experienced by some known gas turbine engines because of separation in and around compressor blades within the conventional engines.
However, pressures generated within the detonation chamber of some known pulse detonation systems may cause at least some known pulse detonation engines to be very loud and may facilitate structural failures within the engines. More specifically, each detonation tube has a firing frequency that is dependent upon the dynamics of detonation and a geometry of the tube. While conventional detonation chambers create thrust by imparting overall pressure rise the hot combustion gases, known pulse detonation tubes also have a dynamically varying positive pressure rise and fall in each tube as each tube repeatedly fires. The dynamic periodicity of such pressures may induce dynamic pressure loads to the pulse detonation system which may propagate from the system as acoustic pressure waves, i.e., noise.
In one aspect, a method is provided for operating a pulse detonation system. The method includes providing a pulse detonation chamber including a plurality of detonation tubes extending therein, and detonating a mixture of fuel and air within each detonation tube such that at least a first tube is detonated at a different time than at least a second detonation tube.
In another aspect, a control system is provided for a pulse detonation system including a plurality of detonation tubes. The control system includes a processor that is programmed to control detonation of a mixture of fuel and air within each detonation tube, such that at least a first detonation tube is detonated at a time that is different from a time of detonation of at least a second detonation tube.
In yet another aspect, a pulse detonator is provided for a pulse detonation system. The chamber includes an inner casing, and an outer casing that is substantially coaxial with the inner casing, and is spaced radially outwardly from the inner casing. The inner and outer casings define a detonation chamber therebetween. A plurality of detonation tubes extend at least partially within the detonation chamber. At least a portion of at least a first detonation tube is stacked radially outwardly from at least a portion of at least an adjacent second detonation tube, such that a first central axis of the first detonation tube is spaced radially outwardly from a second central axis of the adjacent second detonation tube.
In even another aspect, a pulse detonation system is provided that includes a pulse detonator including a plurality of detonation tubes extending at least partially within the pulse detonator, and a control system that includes a processor programmed to control the detonation of a mixture of fuel and air within each detonation tube such that at least a first detonation tube is detonated at a time that is different from a time of detonation of at least a second detonation tube.